The work covered by this Grant develops and tests physical techniques that can give information about the microstructure and microcomposition of fresh and fossil teeth and other hard tissues. The methods currently being used to investigate microstructure include various types of optical micrography, electron microscopy, and the scanning electron microscopy of surfaces and section. Microcomposition is being studied by X-ray spectrocopy, electron probe analysis and by the quantitative chromatography of isolated organic constituents.